Determination of hydrolysed fumonisin B1(HFB1) in corn by competitive direct enzyme‐linked immunosorbent assay

Abstract

Fumonisin B₁, a mycotoxin produced by certain Fusarium moulds, consists of two tricarballylic acid groups esterified to a 20‐carbon backbone. Under alkaline conditions, or through metabolism, the aminopentol backbone, also known as hydrolysed Fumonisin B₁(HFB₁) can be formed and is itself cytotoxic. Although the occurrence of HFB₁ in corn‐based foods is suspected, because of the ubiquitous nature of FB₁ in corn, analytical methods for its detection are difficult. In the present report we describe a monoclonal antibody‐based competitive direct enzyme‐linked immunosorbent assay (CD‐ELISA) for the rapid analysis of HFB₁ in corn. The concentration required to inhibit enzyme conjugate binding by 50% (IC₅₀) was 36 ng/ml. The limit of detection of HFB, by the CD‐ELISA was 2 ng/ml, when HFB₁ was added in bovine serum albumin—phosphate buffered saline. The antibody also cross‐reacted with the hydrolysis products of FB₂, FB₃, and FB₄, having IC₅₀ values of 331, 174, and 1700 ng/ml respectively. The antibody did not react with the intact fumonisins, sphingosine, sphinganine, or tricarballylic acid. Samples of corn spiked with HFB₁ over the range of 5–1000 ng/g indicated the CD‐ELISA has a limit of detection of 5 ng/g and an IC₅₀of 41 ng/g in this matrix. The CD‐ELISA provides a sensitive and rapid tool for the analysis of corn‐based foods for HFB₁.